Earth's Near Misses With Asteroids

A meteor exploded in the sky above Russia Friday morning. But astrophysicist Neil deGrasse Tyson says that's tiny compared to asteroid 2012 DA14, which will be flying by the Earth Friday afternoon.

The asteroid will come within 17,500 miles of the planet, closer than some satellites orbit the Earth.

Dr. Tyson, director of the Hayden Planetarium, says there are no precise numbers on how often asteroids pass within a hair's breath of the planet. While there is some suggestive data, many such occurrences may happen over oceans and go unnoticed. "Perhaps you get one of them a decade."

Asteroids are not uncommon, he said, "the solar system is a shooting gallery." But 2012 DA14 is of particular note because of its proximity. It will come about 5,000 miles closer to the Earth than some communications satellites.

"So now it's kind of like invading our space, so to speak," said Tyson. "And it will, rightly, get extra attention."

View a simulation of the asteroid's flight path:

While NASA says the Russian meteorite is unrelated to asteroid 2012 DA14, Tyson says that's hard to know. He says many asteroids are not solid rocks but piles of rubble traveling together through space, and as those groupings travel, the gravity of the planets they pass can stretch them out from a circular pile into what he described as "a train of rocks."

"When that happens, one impact will be followed by others."

He admits, it's unlikely that the meteorite that crashed in the Ural mountain region is related to 2012 DA14 because of the hours separating the two events.

While Tyson says the asteroid will not hit the Earth, he cautioned about getting too cocky. "By the way, if we were and pass in our orbit 15 minutes earlier than we will be this afternoon, then it would hit us."

Weather permitting, real-time imagery of the asteroid's flyby will be streamed beginning at about 12 p.m. EST.

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